If you are using a Dish-300 w/ a Legacy Dual LNB then yes, this SAM34 switch should work fine. You could also use a Dish Network SW44 or SW64, I'm not sure what the price of the SW44's are but I know that the SW64 is around $160 dollars.
Dish 111, 311, 322, 522, and 811 receivers no longer contain SmartCards, I'm not sure about the 721 and 921 receivers.
Your phone call should be quite simple, call dish and tell them you would like to add an addition receiver to your account, they'll ask for the R00 and S00 numbers off the receiver, a $5.00 outlet fee will be assessed to your account and the receiver should be active within 10 minutes.
...v